If time permits, modify the function so that a player can move the lander up,
down, left or right. Use controller from arrow.ss to control the
movements in all directions.

Thanks to Dung Nguyen and David Kay, Irvine, CA

The following items correct errors in the first and second
printing of the book. They have all been corrected in
the third printing of the book and the on-line version.

page 24:

The problem statement correctly specifies that "[d]ecreasing the price by a
dime ($.10) increases attendance by 15." Later, the book includes the
sentence "The base attendance at a price of five dollars is 120, and for
each 15 cents less than five dollars, 10 more attendees show up." This
second claim is incorrect.

The book mistakenly specifies random as a function that
consumes a natural number. Instead, random consumes an integer
greater than or equal to 1 (and less than or equal to 2147483647).

Thanks to Marvin D. Hernandez, Miami, FL

page 159 (exercise 11.3.2)

The exercise had been misinterpreted twice. The new wording is:
and produces a list of that many numbers, each randomly chosen
from the range from 20 to 120.

Develop the function tie-dyed. It consumes a natural number and
produces a list of that many numbers, each randomly chosen
in the range from 20 to 120. Use
tie-dyed to apply draw-circles from exercise~9.5.8.

Thanks to Stephen Bloch, New York, NY

pages 172-175

The section switches from the development of a descending sort to that
of an ascending sort during the transition from the development of
sort to the development of insert.

The contract and header for count-a-vowel are repeatedly
misstated. Here is the correction:

;; count-a-vowel : letter (vector number number number number number) -> void
;; effect: to modify counts at the appropriate place if l is a vowel,
;; none otherwise
(define (count-a-vowel l counts)
...)

page 259: "a good local definitions" should be "a good
understanding of local definitions" (D.P. Friedman)

page 261: "Determine which of the following definitions or expressions
is legal and which one is not:" should be "Determine which of the following
definitions or expressions are legal and which ones are not:"
(D.P. Friedman)

page 339:
"to add just a few of the first few terms"
should be
"to add just the first few terms"
(D.P. Friedman)

page 346: "The teachpack graphing.ss provides two operations for
drawing lines: graph-line. The operation consumes a line like
y and a color, say, RED." should be "The
teachpack graphing.ss provides one operation for drawing lines:
graph-line. The operation consumes a line like y and a
color, say, 'red." (Joe Zachary)

page 349:
"the answer will be depend on e" should be
"the answer will depend on e" (H. Blazevic)

page 358:
"until drops"
should be
"until it drops
off the table"
(D.P. Friedman)

page 359 (figure 66): the two occurrences of RED should be
'red (H. Blazevic)

A second difference between the two functions concerns the order of
addition. While the original version of sum adds up the numbers
from right to left, the accumulator-style version
adds them up from left to right.

page 528:
"Thus, the matching action is a build a word as long as chosen-word
but to use '_ as the letters."
should be
"Thus, the matching action is to build a word as long as
chosen-word from '_.
(D.P. Friedman)

pages 536/537:
chosen-wor
should be
chosen-word
(D.P. Friedman)

page 566:
"Alonzo Church in the last 1920s as follows:"
should be
"Alonzo Church in the late 1920s as follows:"
(D.P. Friedman)

page 575: The last line of the definition of
next-color requires a closing ")". (D. Smith)

page 577: This sets the light at 'sunrise@cmu to green. (H. Blazevic)

page 595
"in the structure name p"
should be
"in the structure named p"
(D.P. Friedman)